The objective of this Training Program is to produce well-trained and versatile environmental toxicologists with doctoral degrees who will function as researchers, teachers and scientific managers in environmental health science. For the next five-year period, funds are requested to support 10 predoctoral and two postdoctoral trainee positions to continue this successful Program. The postdoctoral slots will permit effective recruitment of outstanding new Ph.D.s, including those entering toxicology from other fields. The training faculty will consist of academic members of the Department of Environmental Toxicology and additional key faculty in other departments at UC Davis. Predoctoral trainees will pursue their degrees through existing graduate groups. Required predoctoral coursework includes a core of environmental toxicology and pharmacology/toxicology graduate courses in addition to those required by each trainee's individual graduate group. Choice of dissertation projects is based on the mutual interests of trainees and faculty with approval by the Training Grant Executive Committee to assure health relatedness. Trainees will be selected by the Executive Committee from graduate students enrolled in the graduate groups compatible with this Training Program. Excellent academic preparation in chemistry, biochemistry and biology, research promise, and strong motivation toward a career in environmental health science are major criteria for selection. Predoctoral trainees are annually evaluated and supported for a maximum of three years. Postdoctoral trainees will be supported for one year, after which the host laboratories will continue support to complete the research experience. The Training Program will be based in the Department of Environmental Toxicology. Additional research facilities are available from other research units through the participation of their faculty members, including those in the School of Medicine, School of Veterinary Medicine, Division of Biological Sciences, California Regional Primate Research Center and the Institute of Toxicology and Environmental Health. The scientific infrastructure is highly stimulating due to the presence of an NIEHS Center for Environmental Health Sciences, based in the Department of Environmental Toxicology, and the campus NIEHS Superfund Basic Research Program, to both of which many Training Grant faculty belong.